Hermetically sealed end closure for containers



Sept. 5, 1950 r w. A. EATON mum'xcmv sumo END CLOSURE FOR cowmmans Filed Dec. 6, 1945 2 Sheets-Sheet 1 Unvcnl'or. WLfiredA.Eato1u am M di-i'ormys Patented Sept. 5, 1950 UNITED STATES PATENT OFFICE HERMETICALLY SEALED END CLOSURE FOR CONTAINERS Illinois Application December 6, 1945, Serial No. 633,246

18 Claims. (Cl. 229-65) This invention relates to containers of paperboard or other sheet material and more particularly to a novel liquid-tight and sift-proof paper container and method of making the same.

One of the objects of the present invention is to provide a novel paper container blank which is readily adapted for quick and eiiicient end sealing, the construction being such that a complete and etficient sealing of all pin holes and cracks is achieved, while securely bonding the end portions together, thus providing an end closure of great strength which is completely liquid-tight, when used for liquids, or sift-proof when employed for powdered materials.

Another object of the invention resides in the provision of a novel means and method for sealing the end of a paper container of the type provided with a plurality of end flaps adapted to to be overlapped to provide a flat end closure, the construction being such that the adhesive used to bond the flaps together is caused to positively flow under the application of a suitable pressure applied to the overlapped flaps, to the desired points of the container end to eiiiciently and thoroughly seal all openings at such points as well as to bond the flaps together.

Still another object resides in a novel paper container construction wherein the adhesive, with which the flaps are coated, is caused to positively flow to the corner openings or pin holes of the overlapped flaps comprising the container end, so that a liquid-proof and siftproof container is secured following the drying or setting of the adhesive.

A further object includes the provision of a plurality of pockets or recesses in one or more of the flaps comprising the container end for receiving and confining a surplus of the flowable adhesive, with which the flaps are coated, the pockets or recesses being of such nature and construction that upon the application of pressure to the overlapped flaps, the pockets are flattened and function as pumps to positively force the adhesive therein outwardly and to the corners of the flaps in order to plug and seal all openings which might otherwise result in the leakage of liquid or powder.

A still further object resides in the provision of a novel means and method for sealing the end of a container of the foregoing character, which is relatively simple in construction, and which is especially adaptable for use at a filling plant, where the containers may be assembled and sealed in a comparatively short time and without the necessity of complicated machinery or of inter- 2 nal coatings of wax or other material, previously relied upon to seal the small corner openings or holes.

Other objects and novel features of the invention will appear more fully hereinafter from the In the drawing wherein similar reference characters refer to similar parts throughout the several views:

Fig. 1 is a partial perspective view of a container constituting one form of the invention and illustrating the end flaps thereof prior to overl pp Fig. 2 is a sectional view of the container of 0 Fig. 1, taken substantially along line 22 of Fig. 1. and following the application of pressure to opposite sides of the flaps and the sealing and bonding of the latter;

Fig. 3 is a sectional view of the container of Fig. 1 taken substantially along line 3--3 of Fig. 1, and illustrates the manner of applying pressure to oposite sides of the flaps, to eflect the sealing thereof;

Fig. 4 is a partial perspective view of a modified form of the invention;

Fig. 5 is a sectional view taken substantially along line 5-5 of Fig. 4 after the flaps havebeen overlapped and subjected to pressure, and

Figs. 6, 7 and 8 are partial perspective views of other modifications of the invention.

The present invention is particularly directed to the sealing of one end of a paperboard container of the type having a plurality of flaps or panels which are adapted to be overlapped and adhesively secured together to provide a flat end, free of flanges, beads or false bottoms. In its broader aspect, the invention provides an arrangement whereby the adhesive is caused to positively flow in a predetermined course under the application of pressure applied to the overlapped flaps, in order to automatically supply the adhesive to desired points where minute openings or cracks are present. By such a construction, such openings and cracks are sealed and the flaps securely bonded together when the pressure is applied and the adhesive is thereafter allowed to dry or set.

In a more specific aspect, the invention provides a plurality of pockets or cavities which are formed in one or more of the flaps and which receive a thicker coating of adhesive when the flaps are coated, the pockets being so shaped and formed that upon the application of pressure to the overlapped flaps, the said pockets are flattened and during this operation, act as pumps to positively force the adhesive to the corners of the flaps or to other points where plugging and sealing of minute openings is desired. During the application of pressure, the pockets substantially disappear and the resultant end is comprised solely of flat, overlapped flaps which are securely bonded together with all openings completely sealed.

Referring more particularly to Fig. 1, the present invention is illustrated therein as being applied to a container blank l0, having a substantially rectangular cross section, and being provided with a pair of integrally formed, oppositely disposed, full-size flaps l2 and I4, and a pair of half-size flaps I8 and I8. These flaps are illustrated in Fig. 1 as being partially overlapped, the arrangement being such that after all the flaps are completely overlapped, they constitute a flat end for the container, as shown in Figs. 2 and 3. The blank I!) is preferably of the type which may be supplied by the manufacturer in a flattened, knocked-down condition, provided with a side seam 20, which is firmly sealed by a suitable adhesive. Such container blanks, may be readily shipped in flat condition, to the point where they are to be filled, and may be set up by relatively simple and inexpensive machinery preparatory to treatment in accordance with the present invention.

In using blanks of the foregoing type, it has been found that with the sealing methods of the prior art, due to the difficulty of accurately folding the flaps in overlapping relationship a small pin hole remains at each of the four corners of the end of the container, after the flaps have been adhesively bonded together. Thus the resulting end was not liquid-tight nor sift-proof, and it was accordingly necessary to apply supplemental wax or other types of coatings to the inside and/or outside of the container to plug or seal such holes.

By the present invention a novel arrangement is employed for automatically sealing such pin holes during the application of pressure to bond the flaps, thus avoiding the subsequent wax coatings of the prior art devices. In the form shown, such novel arrangement includes a plurality of pockets or cavities 22 which may, for example, be formed in the flap l4. Such pockets may be of any suitable shape and are preferably embossed or stamped in the flap l4 from the inner surface toward the outer surface and in such manner that the end 24 of each, is directed toward and includes one of the four corners of the flap.

In order to assemble and seal the flaps or panels, a coating 28 of a suitable adhesive, capable of flowing under the application of pressure, is applied to the inner surfaces of the flaps l4, l8 and I8. Such coating may be applied by the conventional knife, spreader bar or roller, and it will be understood that during such operation, the coating within the cavities 22 will be thicker than that on the remainder of the flap l4. Thereafter, the flaps l2, l4, l8 and II are overlapped in the order named and the assembly is placed within a recessed support or base 28 and subjected to pressure from a ram or plunger 33,

having a cross section substantially of the same shape as that of the container l8. Such pressure is of suflicient magnitude to flatten the pockets 22 to positively flow or force the adhesive contained therein to the ends 24 and the four corners of the flap I4. Thus the four pin holes at the four corners of the container end will be automatically supplied with an amount of adhesive which will insure a thorough and eiilcient plugging and sealing of such holes. At the same time, it will be understood that all of the adhesive coatings 28 are caused to flow under the application of pressure in order to seal all seams and edges of the flaps and to securely bond the latter together, as shown more particularly in Figs. 2 and 3. As shown, the support or base 28 is cup-shaped and thus provides a support engaging the exterior surfaces of the side walls of the container adjacent the flaps l2, I4, [6 and I8. Hence, such side walls are prevented from moving outwardly in a direction of right angles to the vertical axis of the container in response to the pressure of the adhesive as the latter is positively flowed into contact with the inner surfaces of the walls. In this manner, the adhesive is positively forced against the inner surfaces of the side walls to not only form a continuous sealing band between the free edges of the flaps and the container walls to provide a leakproof joint, but also to firmly bond the edges of the flaps directly to the container walls. Preferably, the pressure of the plunger 30 is maintained, while the adhesive sets or dries, and if desired, suitable means for accelerating the setting of the adhesive may be employed. Moreover, in the event that the adhesive employed is of the thermoplastic type, it will be understood that suitable heating means are utilized in connection with the plunger 30 and the base 28 in order that the adhesive may be rendered flowable during the application of pressure. Thereafter, any desirable cooling means may be utilized to hasten the setting of the thermoplastic adhesive.

The modification illustrated in Figs. 4 and 5 is especially adapted for a container blank wherein one end is constituted by four overlapping half-size flaps 32, 34 and l6, l8. As shown, each of the flaps 32 and 34 is provided with a pair of pockets 22 having their respective ends 24 directed toward the inner corners of the flaps. In addition, each of the flaps 32 and 34 is provided with an additional pocket 36 having their respective ends 38 directed toward the central portion of the free edges of the flaps. In this form of the invention, all of the pockets 22 and 36 are formed as in Fig. 1 except that they are pressed from the outer surfaces of the flaps toward the inner surfaces thereof in order to provide adhesive-receiving cavities when the flaps occupy the positions shown in Fig. 4.

In assembling the flaps of Fig. 4 to form the container end, the flaps 32 and 34 are first provided with a relatively thin coating l4 of a flowable adhesive. As in the case of Fig. 1, it will be understood that all of the cavities 22 and 38 will receive a thicker coating of the adhesive, than the remaining portions of the flaps. Thereafter, the flaps l6 and I8 are folded down upon the coated flaps 32 and 34 and the assembly is subjected to the pressure of the ram 30. Such pressure is sufficient to flatten the pockets 22 to positively flow or force the adhesive therein to ends 24 and the four corners of the container end for sealing and plugging the holes at such corhere. It will be understood that the function of the recessed support 20, in connection with the formation of the end closure of Figs. 4 and 5, is the same as that previously described in connection with Fig. 1. It will be observed that due to the half-size flaps used in the construction, a pin hole exists at the center of the free edges of the flaps l6 and I8 and 32 and 34. This hole will be efliciently plugged and sealed by the adhesive flowing from the two pockets 3 during the pressure step the said pockets being flattened in the same manner as pockets 22. Thus, as in the case of Fig. 1, all pin holes will be eiliciently sealed and simultaneously therewith, the flaps will be securely bonded together to provide a flat. liquid-tight container end of great strength and durability.

In the modified form shown in Fig. 6, the container is provided with integrally formed fullsized-flaps l2 and I4 and half-size flaps l8 and II as in Fig. 1. However, a different pocket arrangement is employed in that a single recess or pocket 40 is provided in the flap i2 which is continuous and extends completely around the periphery of the flap l2. Preferably, the pocket 40 is formed by embossing or stamping the central portion of the flap I2 from the inner surface toward the outer surface, this operation resulting in an outwardly projecting area 42.

When it is desired to assemble the flaps of Fig. 6, a coating 26 of adhesive is applied to the entire outer surface of flap l2 as well as to the inner surfaces of flaps l6 and I8, it being pointed out that the thickness of the adhesive film 26 in the continuous pocket 40 is greater than that on the area 42. Thereafter, flaps l2, l4, l6 and II are overlapped in the order named, and the assembly is subjected to pressure as in the other forms of the invention. It will be readily understood that during the pressure step, the projecting area 42 will be flattened and that the adhesive film 26 in the pocket 40 will positively flow outwardly in order to completely seal all pin holes and cracks in the overlapped flap construction.

Fig. 7 shows an arrangement similar to Fig. 6 except that the peripheral pocket 40 has been subdivided into four isolated pockets 44, 46, 48 and 50 by extensions 52, 54, 56 and 58 of the projecting area 42. The method of assembly of the flaps is identical to that used in connection with the form of Fig. 6.

In the form shown in Fig. 8, the pockets 44, 46, 48 and 50 have been decreased in size by enlarging the projecting area 42. It will be understood however, that if desired, the pockets in this figure may be formed by depressing the four corners of the flap l2 from the outer surface toward the inner surface. In assembling the flaps, the same method as used in connection with Fig. 6, is utilized.

There has thus been provided by the present invention, a novel means and method for obtaining a flat and liquid-tight end for a paper container. In the event that the container is adapted to contain liquids, it is preferable to employ an adhesive, which when in a set condition, possesses a tensile strength substantially the same as the paper of the container. In this manner an unusually strong and substantially integral end is achieved, which may be subjected to severe shocks and jars without leaking. The provision of the pockets or cavities in one or more of the flaps enables the adhesive therein to be automatically directed and forced to the 7 ing said one flap, with desired points during the application of pressure to the overlapped flaps, thus securing a quick and eiilcient sealing of all pin holes and cracks as well as a secure bonding of the flaps in a single operation. At the same time, a reduction in adhesive cost is eflfected by the above construction and method, since the thickness of the adhesive coating on the portions of the flaps which are not recessed need only be suflicient to insure bonding of the flaps together, the size of the pockets or depressions and the thickness of adhesive therein being so chosen as to provide substantially the amount of excess adhesive to insure sealing of the openings at the corners of the end closure, and at the center of the closure in the construction shown in Fig. 4.

While several embodiments of the invention have been shown and described herein with considerable particularity, it will be understood that the invention is not limited thereto but maybe embodied in various forms. For example, while several desirable arrangements of the adhesivereceiving pockets have been illustrated, it will be appreciated that they may be of other shapes and may be located in various positions in one or a plurality of flaps, the essence of the invention residing in the confining of portions of the adhesive coating and the positive directing of the adhesive under pressure to the points it is desired to seal. Various other changes and modifications may be resorted to, as will readily appear to those skilled in the art without departing from the scope of the invention. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. The method of sealing an open end of a tubular paperboard container having a rectangular cross section and being provided with a plurality of end flaps formed integrally with the container walls, which comprises providing at least one of said flaps with a pair of pockets having end portions directed toward separate corners of said one flap, coating a plurality of said flaps and includa flowable adhesive to provide a relatively thin adhesive film on said coated flaps and a relatively thicker adhesive film within said pockets, overlapping said flaps, and subjecting said overlapped flaps to pressure-sumcient to flatten said pockets and cause the adhesive therein to flow outwardly to said separate corners to seal the openings at said corners, and to bond said flaps together.

2. A paperboard container blank for 2. container having a substantially rectangular cross section and provided with a plurality of end flaps adapted to be overlaped, at least one of said flaps being provided with a pair of adhesive receiving pockets having end portions directed toward and terminating at separate corners of said one flap.

3. A paperboard container blank for a container having a substantially rectangular cross section and provided with a plurality of end flaps adapted to be overlapped, at least one of said flaps being embossed to provide a pair of separate adhesive receiving pockets each of which is provided with an end portion terminating at a separate corner of said one flap.

4. A paperboard container blank for a container having a substantially rectangular cross section and provided with a plurality of integral end flaps adapted to be overlapped, at least one of said flaps being provided with a pair of separate adhesive receiving pockets having end portions directed toward and including the separate coracre of said one flap where the latter joins the wall of the blank.

5. The method of sealing an open end of a tubular paperboard container having a rectangular cross section and being provided with a plurality of end flaps formed integrally with the container walls, which comprises embossing at least one of said flaps to provide a pair of separate pockets having end portions directed toward and including the separate corners of said one flap where the latter joins the wall of the container, coating a plurality of said flaps and including said one flap, with a flowable adhesive to provide a relatively thin adhesive film on said coated flaps and a relatively thicker adhesive film within said pockets, overlapping said flaps, and subjecting said overlapped flaps to pressure sufiicient to fiatten said pockets and cause the adhesive therein to flow outwardly to said separate corners to seal the openings at said corners, and to bond said flaps together.

8. A paperboard container comprising a body portion of substantially rectangular cross section and a flat end closure therefor, said closure comprising a plurality of overlapped flat flaps formed integrally with the body portion and having a relatively thin coating of flowable adhesive therebetween, at least one of said flaps being provided with a pair of separate adhesive receiving pockets having end portions directed toward and including separate corners of one of said flaps, said overlapped flaps being compressed to flatten said pockets and thereby positively flow the adhesive therein outwardly to said corners to seal the openings at said corners and to bond said flaps together.

7. A paperboard container comprising a body portion of substantially rectangular cross section and a flat end closure therefor, said closure comprising a pair of opposed full-size flaps and a pair of opposed half-size flaps integral with the side walls thereof, one of said full-size flaps having four separate pockets formed therein, said pockets being directed toward and including separate corners of said one flap, the latter flap having a relatively thin coating of a flowable adhesive over one surface with a relatively thicker coating of adhesive within said pockets, and the half-size flaps being provided with relatively thin coatings of adhesive over their inner surfaces, all of said flaps being overlapped with the said one flap interposed between the other full-size flap and the pair of half-size flaps, and being compressed to flatten all of said pockets and thereby positively flow the adhesive therein outwardly to said corners to seal the openings at said corners and to bond said flaps together.

8. The method of sealing an open end of a tubular paperboard container having a rectangular cross section and being provided with a pair of opposed full-size flaps and a pair of opposed half size flaps on the side walls thereof, which comprises providing one of the full-size flaps with four separate pockets directed toward and including separate corners thereof, coating one surface of the latter flap and including said pockets and both the inner surfaces of said half-size flaps with a flowable adhesive, folding said full-size flaps in overlapping relation with the adhesive coating therebetween, thereafter folding the halfsize flaps in overlapping relation with the fullsize flaps, and subjecting all of said flaps and adhesive coatings to pressure sufficient to flatten all of said pockets and positively flow the adhesive therein outwardly to said corners to seal the openings at said corners and to bond said flaps together.

9. A paperboard .container comprising a body portion of substantially rectangular cross section and a flat end closure therefor, said closure comprising a first and second pair of opposed halfsize flaps integral with the side walls thereof, each flap of said first pair having three separate pockets formed therein, two of said pockets being directed toward the flap corners adjacent the body portion and the third pocket being directed toward the center of the free edge of the flap, both of the last-named flaps having on their outer surfaces, a relatively thin coating of a flowable adhesive with a relatively thicker coating of adhesive within said pockets, said second pair of flaps being overlapped with respect to the first pair, and the overlapped flaps being compressed sufilciently to flatten all of said pockets and thereby positively flow the adhesive therein outwardly to said corners and to the center of the free edges of the first pair of flaps to seal all openings and to bond all flaps together.

10. The method of sealing an open end of a tubular container having a plurality of fiat end flaps formed integrally with the container walls and provided with adhesive confining means adjacent a pair of separate corners of one of said flaps, which comprises coating a plurality of flaps with a relatively thin film of a flowable adhesive. confining a relatively thicker film of adhesive in said adhesive confining means adjacent a pair of separate corners of one of said flaps, overlapping said flaps, and subjecting said overlapped flaps to pressure sufiicient to cause the confined adhesive to flow outwardly to said separate corners to seal the openings at said corners, and to bond said flaps together. g

11. A container blank for a container having a polygonal cross section and provided with a plurality of end flaps adapted to be overlapped, at least one of said flaps being provided with a pair of adhesive receiving pockets having end portions directed toward separate corners of said one flap.

12. A container blank for a container having a polygonal cross section and provided with a plurality of end flaps adapted to be overlapped, at least a portion of said flaps being provided with adhesive receiving pockets having end portions directed toward corners of said flaps.

13. The method of sealing an open end of a tubular container having a polygonal cross section and provided with an end closure comprising a plurality of flaps of a. shape substantially corresponding to said cross section, which comprises providing at least one of said flaps with a pair of pockets having end portions directed toward separate corners of said one flap, coating at least said one flap with a. flowable adhesive to provide an adhesive film of one thickness thereon and an adhesive film of relatively greater thickness in said pockets, overlapping said flaps, and subjecting said overlapped flaps to pressure sufllcient to flatten said pockets and cause the adhesive to bond said flaps together and to also cause the adhesive in said pockets to flow outwardly to said separate corners to seal the openings at said corners.

14. The method of bonding together a pair of panels with adhesive and flowing an excess of adhesive to selected portions of said panels, which comprises providing pockets in one of said panels having end portions directed toward said selected portions of said panels. coating said one panel with a flowable adhesive to provide a relatively thin film of adhesive thereon and a relatively thicker film of adhesive in said pockets, placing saidpanels together with said adhesive film therebetween, and subjecting said panels to pressure suiilcient to bond said panels together and suil'icientto flatten said pockets to cause adhesive therein to flow toward said selected portions of said panels.

15. The method of bonding together with a flowable adhesive 9. pair of panels forming an end closure for a container having a polygonal cross sectiona'nd positively flowing said adhesive toward a corner formed by the junction of said panels and,,1 i6 side walls of said container to seal an opening at said corner, which comprises iorming a pocket on one surface of one of said panels having-an end portion directed toward said corner, boating said one surface of said one panel with a, fi owable adhesive to provide a relatively thin film of adhesive on said one surface and a relatively thicker film of adhesive in said pocket, overlapping said panels in end-closing relationshipwith said films of adhesive therebetween, and subjecting said panels to pressure to eifeot anaadhesive bond therebetween and to,

10 i said pocket and thereby positively flow the adhesive therein outwardly to said corner to seal the opening at said corner and to bond the flaps together.

17. A paperboard container blank for a container of substantially rectangular cross section and provided with a plurality of end flaps adapted to be overlapped, a pair of pockets on one of said flaps having end portions directed towards separate corners of said one flap, a relatively thin coating of adhesive on the main portion of at least said one flap, and a relatively thick coating of adhesive in said pockets.

18. A paperboard container blank for a container of polygonal cross section and provided with a plurality of end flaps adapted to be overlapped, at least one of said flaps being embossed to provide an adhesive receiving pocket having an end portion directed toward and terminating at a corner of said one flap, relatively thin coatings of adhesive on portions of some of the flaps, and a relatively thick coating of adhesive in said pocket.

flatten said pocket to positively flow the adhesive from said pocket through the end portion thereof to said corner. I

it. A paperboard container comprising a body portion oi" substantially polygonal cross section and a ilatflgend closure therefore, said closure ccprisii'ia aplurality of overlapped flat flaps formed integrally with the body portion and having a relativeiythin coating of flowable adhesive therebetween, at least one of said flaps being provided witha poclret which includes at least one corner of said one Map and which carries a relatively thicker coating of said adhesive, said overlapped flaps being compressed to flatten WILFRED A. EATON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA 

